Semiconductor cooling structure

ABSTRACT

The semiconductor cooling structure includes a semiconductor module including therein at least two semiconductor elements, a cooling pipe having a cooling surface in close contact with the semiconductor module, the cooling pipe including a coolant inlet hole, a coolant outlet hole, and a coolant passage through which coolant flows in a first direction from the coolant inlet hole to the coolant outlet hole, and a coolant moving structure disposed within the cooling pipe to move the coolant flowing through the coolant passage such that the coolant has a velocity vector in a second direction perpendicular to the cooling surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to Japanese Patent Applications No. 2008-3593 filed on Jan. 10, 2008, and No. 2008-323259 filed on Dec. 19, 2008, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor cooling structure having semiconductor modules each including therein semiconductor elements, and a cooling pipe disposed in close contact with the semiconductor modules.

2. Description of Related Art

Generally, a power conversion device such as an inverter is constituted by a plurality of semiconductor modules each of which includes therein semiconductor elements and is configured to pass a large current to each of the semiconductor modules. In order to prevent the temperature of the semiconductor elements from increasing excessively, it is known to dispose a cooling pipe through which coolant circulates in close contact with the semiconductor modules. For example, refer to Japanese Patent Application Laid-open No. 2006-60114. In the semiconductor cooling structure disclosed in this patent document, fins are provided in a coolant passage within the cooling pipe. These fins are arranged such that a cooling efficiency distribution not uniform in the width direction of the coolant passage is formed in a cooling surface of the cooling pipe, depending on a surface temperature distribution of the semiconductor elements. Here, the width direction is a direction which is perpendicular to both the direction in which the coolant flows and the direction perpendicular to the cooling surface.

However, the above conventional semiconductor cooling structure has a problem in that a temperature distribution tends to occur in the coolant passage in the direction perpendicular to the cooling surface. This is because the temperature of the coolant flowing closely to the cooling surface which is in close contact with the semiconductor modules is likely to rise significantly, compared to the coolant flowing far from the cooling surface. This lowers the efficiency of heat exchange between the coolant and the semiconductor modules.

It may occur that the semiconductor modules are disposed on both surfaces of the cooling pipe. However, also in this case, if there is difference in heat dissipation value between the semiconductor elements located on the side of one surface of the cooling pipe and the semiconductor elements located on the side of the other surface, a temperature distribution occurs in the direction perpendicular to the cooling surface. Accordingly, it is difficult to increase the cooling efficiency for the semiconductor elements even if the semiconductor modules are disposed on both surfaces of the cooling pipe.

SUMMARY OF THE INVENTION

The present invention provides a semiconductor cooling structure comprising:

a semiconductor module including therein at least two semiconductor elements;

a cooling pipe having a cooling surface in close contact with the semiconductor module, the cooling pipe including a coolant inlet hole, a coolant outlet hole, and a coolant passage through which coolant flows in a first direction from the coolant inlet hole to the coolant outlet hole; and

a coolant moving structure disposed within the cooling pipe to move the coolant flowing through the coolant passage such that the coolant has a velocity vector in a second direction perpendicular to the cooling surface.

According to the present invention, there is provided a semiconductor cooling structure excellent in cooling efficiency.

Other advantages and features of the invention will become apparent from the following description including the drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a diagram showing a semiconductor cooling structure of a first embodiment of the invention;

FIG. 2 is a cross-sectional view of a cooling pipe in the direction perpendicular to the coolant flowing direction included in the semiconductor cooling structure of the first embodiment;

FIG. 3A is a cross-sectional view of FIG. 1 taken along line A-A;

FIG. 3B is a cross-sectional view of FIG. 1 taken along line B-B;

FIG. 3C is a cross-sectional view of FIG. 1 taken along line C-C;

FIG. 4 is an explanatory view of a power conversion device using the semiconductor cooling structure of the first embodiment;

FIG. 5 is a diagram for explaining flow of coolant in the cooling pipe of the semiconductor cooling structure of the first embodiment when semiconductor modules are disposed in close contact with only one of the cooling surfaces of the cooling pipe;

FIG. 6 is a diagram for explaining flow of coolant in the cooling pipe of the semiconductor cooling structure of the first embodiment when semiconductor modules having different heat dissipation values are disposed in close contact with both of the cooling surfaces of the cooling pipe;

FIG. 7A is a diagram equivalent to FIG. 3A, which shows a second embodiment of the invention;

FIG. 7B is a diagram equivalent to FIG. 3B, which shows the second embodiment of the invention;

FIG. 7C is a diagram equivalent to FIG. 3C, which shows the second embodiment of the invention;

FIG. 8 is a diagram for explaining a semiconductor cooling structure of a third embodiment of the invention;

FIG. 9 is a cross-sectional view of a cooling pipe in the direction perpendicular to the coolant flowing direction included in the semiconductor cooling structure of the third embodiment;

FIG. 10 is a partial cross-sectional view of FIG. 8 taken along line D-D;

FIG. 11 is a perspective view of straight fins with oblique ribs provided in a cooling pipe of a semiconductor cooling structure of a fourth embodiment of the invention;

FIG. 12 is a partial cross-sectional view of FIG. 11 taken along line E-E;

FIG. 13A is a cross-sectional view of FIG. 12 taken along line F-F;

FIG. 13B is a cross-sectional view of FIG. 12 taken along line G-G;

FIG. 14 is a explanatory view of the oblique ribs in the fourth embodiment;

FIG. 15 is a cross-sectional view of FIG. 14 taken along line H-H;

FIG. 16 is a diagram showing a semiconductor cooling structure of a fifth embodiment of the invention;

FIG. 17 is an explanatory view of tapered ribs provided in a cooling pipe of the semiconductor cooling structure of the fifth embodiment;

FIG. 18A is a cross-sectional view of FIG. 17 taken along line I-I;

FIG. 18B is a cross-sectional view of FIG. 17 taken along line J-J;

FIG. 19 is a diagram showing a semiconductor cooling structure of a sixth embodiment of the invention;

FIG. 20 is a cross-sectional view of a cooling pipe in the direction perpendicular to the coolant flowing direction included in the semiconductor cooling structure of the sixth embodiment;

FIG. 21 is a partial cross-sectional view of FIG. 19 taken along line K-K;

FIG. 22 is a diagram showing a modification of the semiconductor cooling structure of the sixth embodiment of the invention:

FIG. 23 is a cross-sectional view of a cooling pipe in the direction perpendicular to the coolant flowing direction included in the modification of the semiconductor cooling structure of the sixth embodiment;

FIG. 24 is a partial cross-sectional view of FIG. 22 taken along line L-L;

FIGS. 25A and 25B are diagrams explaining locations of oblique fins provided in straight fins provided in a cooling pipe of a semiconductor cooling structure of a seventh embodiment of the invention;

FIGS. 26A to 34B are diagrams each explaining locations of the oblique fins provided in the straight fins provided in a cooling pipe of a variant of the semiconductor cooling structure of the seventh embodiment of the invention;

FIG. 35 is a diagram for explaining advantageous effect of the oblique ribs in the foregoing embodiments of the invention; and

FIG. 36 is a diagram for explaining advantageous effect of projections provided in shell plates of the cooling pipe so as to project toward a coolant passage within the cooling pipe in the foregoing embodiments of the invention.

PREFERRED EMBODIMENTS OF THE INVENTION First Embodiment

FIG. 1 is a diagram showing a semiconductor cooling structure 1 of a first embodiment of the invention. As shown in FIG. 1, the semiconductor cooling structure 1 includes semiconductor modules 2 each having therein semiconductor elements 21, and a cooling pipe 3 disposed in close contact with the semiconductor modules 2. The cooling pipe 3 includes a coolant inlet hole 311, a coolant outlet hole 312, and a coolant passage 32 (see FIG. 3A) extending between the coolant inlet hole 311 and the coolant outlet hole 312. As shown in FIG. 3A, the cooling pipe 3 is provided with a coolant moving means for causing coolant to move in a first direction perpendicular to cooling surfaces 33 which are in close contact with the semiconductor modules 2. The first direction may be referred to as “perpendicular to the cooling surface direction X” or “X-direction” hereinafter.

As shown in FIGS. 2 and 3A to 3C, the cooling pipe 3 includes a middle plate 34 which divides the cooling passage 32 in the X-direction to form a first passage 321 and a second passage 322. The coolant flows through the first passage 321 and the second passage 322 alternately. In FIG. 4, the fins 4 are omitted from illustration.

As shown in FIG. 3B, the middle plate 34 has communicating portions 341 at both end portions thereof in a second direction perpendicular to a third direction in which the coolant flows from the coolant inlet hole 311 to the coolant outlet hole 312. The third direction may be referred to as “coolant flowing direction Y” or “Y-direction”, and the second direction may be referred to as “cooling surface width direction Z” or “Z-direction” hereinafter. As shown in FIGS. 3A and 3C, each of the first and second passages 321 and 322 is provided with oblique fins 4 formed obliquely to the coolant flowing direction Y. The oblique direction of the oblique fins 4 provided in the first passage 321 is opposite to that of the oblique fins 4 provided in the second passage 322.

The oblique angle α of the oblique fins 4 with respect to the Y-direction may be 45 degrees.

The cooling pipe 3 is constituted by a plurality of members made of aluminum or aluminum alloy. More particularly, as shown in FIG. 2, the cooling pipe 3 is constituted by a pair of shell plates 35 which constitute a shell portion of the cooling pipe 3, and the middle plate 34 located between the shell plates 35 and joined to the shell plates 35 at their circumferences by brazing, for example. The shell plates 35 have such a shape as to form a space therebetween inside their circumferential. This space is separated into two parts one of which forms the first passage 321 and the other of which forms the second passage 322.

As shown in FIGS. 3A to 3C, each of the shell plates 35 and the middle plate 34 has a shape elongated in the Y-direction. The shell plates 35 are respectively formed with the coolant inlet hole 311 and the coolant outlet hole 312 at their ends. The middle plate 34 is formed with an opening 342 at a position facing coolant inlet 311 and at a position facing the coolant outlet 312. As explained above, the middle plate 34 is formed with the pair of the communicating portions 341 extending along the Y-direction at both end portions thereof in the Z-direction.

The oblique fins 4 which are parallel to one another are disposed between each of the shell plates 35 and the middle plate 34. These oblique fins 4 may be brazed to one of or both of the middle plate 34 and the shell plate 35. As shown in FIG. 3A, the oblique fins 4 disposed in the first passage 321 have a shape extending from the coolant inlet hole 311 to the communicating portion 341 on the upper side (may be referred to as “upper-side communicating portion 341 u” hereinafter), or from the communicating portion 341 on the down side (may be referred to as “down-side communicating portion 341 d” hereinafter) to the upper-side communicating portion 341 u or the coolant outlet hole 312.

On the other hand, as shown in FIG. 3C, the oblique fins 4 disposed in the second passage 322 have a shape extending from the coolant inlet hole 311 to the down-side communicating portion 341 d, or from the upper-side communicating portion 341 u to the down-side communicating portion 341 d or the coolant outlet hole 312. Here and in the following, the terms “upper side” and “down side” are used to indicate the positions of the communicating portions in FIG. 3, and are not such as to limit this embodiment in structure.

As shown in FIG. 1, the semiconductor modules 2 are disposed in close contact with the major surface (cooling surface 33) of the cooling pipe 3 having the above described structure. Each semiconductor module 2 has two semiconductor elements 21 built therein. Each semiconductor module 2 has also a pair of heat sinks 22 disposed so as to hold the two semiconductor elements 21 therebetween. The semiconductor elements 21 are in direct contact with the one of the heat sinks 22, and in thermal contact with the other of the heat sinks 22 through a spacer 23 having high heat conductivity.

The semiconductor element 21 may be a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or an IGBT (Insulated Gate Bipolar Transistor) or a diode. In this embodiment, one of the two semiconductor elements built in each of the semiconductor modules 2 is an IGBT, and the other is a flywheel diode.

In this embodiment, the number of the semiconductor modules 2 is four, two of them being arranged in the Y-direction on one of the cooling surfaces 33, the other two being arranged in the Y-direction on the other cooling surface 33. An insulating member having high heat conductivity may be interposed between the heat sinks 22 and the cooling pipe 3 in each semiconductor module 2.

The semiconductor cooling structure 1 of this embodiment may be a piled structure as shown in FIG. 4, so that it can be a part of a power conversion device such as an inverter. In this case, each two of the cooling pipes 3 adjacent in the pile direction are connected to each other at their coolant inlet holes 311 and at their coolant outlet holes 312 by a connecting pipe 36. The cooling pipe 3 disposed on one of the outermost sides is provided with a coolant introducing pipe 371 for introducing the coolant into the pile of the cooling pipes 3 and a coolant discharging pipe 372 for discharging the coolant from the pile of the cooling pipes 3.

The connecting pipe 36 may be a part of the shell plate 35 of the cooling pipe 3, or may be a pipe member prepared separately from the cooling pipe 3 and secured to the coolant inlet hole 311 or coolant outlet hole 312. Each of the cooling pipes 3 disposed on both the outermost sides has the cooling surface 33 in close contact with the semiconductor modules 2 only at one side thereof. Each of the other cooling pipes 3 has the cooling surfaces 33 at both sides thereof as shown in FIG. 1.

In the structure shown in FIG. 4, the coolant W introduced from the coolant introducing pipe 371 is distributed to the cooling pipes 3 through the connecting pipes 36. That is, the coolant W is introduced into each of the coolant inlet holes 311 of the cooling pipes 3 and flows through each of the coolant passages 32 of the cooling pipes 3. The coolant W exchanges heat with the semiconductor modules 2 disposed in close contact with each of the cooling pipes 3. Thereafter, the coolant W passes through the cooling outlet hole 312 of each cooling pipe 3, reaches the coolant discharging pipe 372 through the connecting pipes 36, and is discharged therefrom.

As the coolant W, there may be used a natural coolant such as water and ammonia, water mixed with antifreeze of the ethylene glycol group, a coolant of the freon group such as HCFC123 and HFC134a, a coolant of the alcohol group such as methanol and alcohol, or a coolant of the ketone group such as acetone.

The operation and advantages of the first embodiment described above are explained below. The semiconductor cooling structure 1 is provided, at the coolant passage 32 of the cooling pipe 3 thereof, with the means for moving the coolant along the X-direction. This makes it possible to suppress the coolant introduced in the coolant passage 32 from forming a temperature distribution in the X-direction. This is possible in the case where the semiconductor modules 2 are disposed in close contact with only one of the cooling surfaces of the cooling pipe 3 as shown in FIG. 5, and also in the case where the semiconductor modules 2 having different heat dissipation values are disposed in close contact with both the cooling surfaces of the cooling pipe 3 as shown in FIG. 6.

Accordingly, according to this embodiment, the whole of the coolant introduced into the coolant passage 32 can be efficiently used for heat exchange with the semiconductor elements 21. Hence, according to this embodiment, the cooling efficiency for the semiconductor elements 21 can be improved.

The cooling pipe 3 is provided with the middle plate 34, and the coolant flows through the first passage 321 and the second passage 322 alternately which are separated from each other by the middle plate 34. The middle plate 34 has the communicating portion 341 at each of its end portions in the Z-direction, and each of the first passage 321 and the second passage 322 is provided with the oblique fins 4. The oblique direction of the oblique fins 4 provided in the first passage 321 is opposite to that of the oblique fins 4 provided in the second passage 322.

Accordingly, the coolant introduced into the coolant passage 32 through the coolant inlet hole 311 flows along the oblique fins 4 obliquely to the Y-direction, and reaches the communicating portion 341 u. Thereafter, the coolant moves from the first passage 321 to the second passage 322 through the communicating portion 341 u, flows along the oblique fins 4 in the second passage 322, and reaches the communicating portion 341 d. Thereafter, the coolant moves to the first passage 321 again. In this way, the coolant moves from the first passage 321 to the second passage 322 and vice versa alternately by way of the two communication portions 341 u and 341 d, while flowing spirally through the coolant passage 32. This makes it possible to efficiently move the coolant in the X-direction, to thereby suppress formation of a temperature distribution.

In the case where the two semiconductor modules 2 are arranged along the Y-direction in close contact with only one of the cooling surfaces 33 of the cooling pipe 3 (only the cooling surface 33 on the side of the first passage 321) as shown in FIG. 5, the coolant exchanges heat with the semiconductor modules 2 in the way described below. The coolant W introduced into the first passage 321 through the coolant inlet hole 311 exchanges heat with the upstream side semiconductor module 2. The coolant W whose temperature has increased due to this heat exchange flows spirally through the coolant passage 32, moves to the second passage 322 on the downstream side, and reaches the coolant outlet hole 312.

On the other hand, the coolant W introduced into the second passage 322 through the coolant inlet hole 311 hardly exchanges heat with the upstream side semiconductor module 2, and moves to the first passage 321 on the downstream side, while flowing spirally through the coolant passage 32 keeping its low-temperature state. This low-temperature coolant W which has moved to the first passage 321 exchanges heat with the down stream side semiconductor module 2. Hence, in the case where the semiconductor modules 2 are disposed on only one of the cooling surfaces 33 of the cooling pipe 3, the whole of the coolant introduced into the coolant passage 32 can be efficiently used for heat exchange with the semiconductor modules 2.

Next, explanation is given for another case where the semiconductor modules 2 having different heat dissipation values are disposed in close contact with both the cooling surfaces of the cooling pipe 3 as shown in FIG. 6. Here it is assumed that two semiconductor modules 2H each including semiconductor elements 21 having a high heat dissipation value are arranged in the Y-direction in close contact with the cooling surface 33 on the side of the first passage 321, and two semiconductor modules 2L each including semiconductor elements 21 having a low heat dissipation value are arranged in the Y-direction in close contact with the cooling surface 33 on the side of the second passage 322.

The coolant W introduced into the first passage 321 through the coolant inlet hole 311 exchanges heat with the semiconductor modules 2H dissipating higher heat, and moves to the second passage 322 on the downstream side, while spirally flowing through the coolant passage 32. Thereafter, this coolant W exchanges heat with the semiconductor modules 2L dissipating lower heat in the second passage 322 on the downstream side, and reaches the coolant outlet hole 312. On the other hand, the coolant W introduced into the second passage 322 through the coolant inlet hole 311 exchanges heat with the semiconductor modules 2L dissipating lower heat, and moves to the first passage 321 on the downstream side, while spirally flowing through the coolant passage 32. Thereafter, this coolant W exchanges heat with the semiconductor modules 2H dissipating higher heat in the first passage 321 on the downstream side, and reaches the coolant outlet 312.

As explained above, also in the case where the semiconductor modules 2 having different heat dissipation values are disposed in close contact with both the cooling surfaces of the cooling pipe 3, it is possible to suppress the coolant from forming a temperature distribution in the X-direction within the coolant passage 32, because the coolant exchanges heat with the semiconductor modules 2 while moving in the X-direction. This makes it possible to suppress occurrence of difference in the cooling efficiency between the cooling surfaces 33 of the cooling pipe 3, and to cool the semiconductor modules 2 by efficiently using the whole of the coolant supplied to the coolant passage 32.

Furthermore, since the coolant flows obliquely along the fins, and accordingly can easily move along the Z-direction in the first passage 321 and the second passage 322, it is also possible to suppress formation of a temperature distribution in the Z-direction. Hence, the cooling efficiency for the semiconductor elements 21 can be sufficiently improved.

Second Embodiment

The second embodiment shown in FIGS. 7A to 7C is characterized in that the oblique fins 4 are made shorter, and each adjacent two of the oblique fins 4 are offset to each other. In the foregoing first embodiment, as shown in FIG. 3, the oblique fins 4 are formed so as to continuously extend from near the coolant inlet hole 311 to either of the communication portions 341 of the middle plate 34, or from one of the communication portions 341 to the other of the communication portions 341, or from either of the communication portions 341 to near the coolant outlet hole 312.

On the other hand, in this embodiment, as shown in FIGS. 7A and 7C, although the direction of extension is the same as in the first embodiment, the oblique fins 4 having a shorter length are formed in an intermittent manner, and each adjacent two of the oblique fins 4 are offset to each other. The others are the same as the first embodiment. The second embodiment provides the same advantages as the first embodiment.

Third Embodiment

The third embodiment shown in FIGS. 8 to 10 is characterized in that the cooling pipe 3 is provided with, instead of the oblique fins 4, straight fins 5 extending in parallel along the Y-direction to divide the coolant passage 32 in the Z-direction to form a plurality of divided coolant passages 323, and that each shell plate 35 is formed with projections 6 projecting toward the coolant passage 32.

As shown in FIG. 9, the straight fins 5 are formed by shaping an aluminum plate or the like into a rectangular wave shape. The straight fins 5 are brazed to the shell plates 35 of the cooling pipe 3 at the top faces (crest portions and trough portions of the rectangular wave) 51 thereof.

Each of the divided coolant passages 323 is provided with the projections 6 at three positions along the Y-direction. That is, as shown in FIG. 8, each of the projections 6 is located between two of the semiconductor elements 21 adjacent in the Y-direction. Accordingly, the projections 6 are located on the upstream sides of the semiconductor elements 21 except the one located on the uppermost-stream side.

As shown in FIG. 10, the projections 6 are formed by press-forming the shell plates 35 of the cooling pipe 3, such that they are located at positions where the top faces 51 of the straight fins 5 do not abut on the shell plates 35. Accordingly, the projections 6 of adjacent two of the divided coolant passages 323 are formed on the opposite shell plates 35, respectively. The projection 6 has a nearly semi-spherical shape, and its diameter in plan view (viewed from direction of projection) is nearly equal to the pitch of side portions 52 of the straight fins 5. The projection height t1 of the projection 6 may be set to ⅕ of the height of the coolant passage 32 in the X-direction. The others are the same as the first embodiment.

In this embodiment, because of the provision of the projections 6, there occurs pressure difference in the coolant in X-direction, and therefore there occurs a flow with a velocity vector in the X-direction. This suppresses formation of a temperature distribution in the coolant passage 32. Since each projection 6 is located on the upstream side of a corresponding one of the semiconductor elements 21, the coolant moves short of this semiconductor element 21 in X-direction. Accordingly, since it is possible to cause the low-temperature coolant to approach the semiconductor elements 21, they can be efficiently cooled.

In this embodiment, the projections 6 are located respectively on the upstream sides of the semiconductor elements 21 except the one located on the uppermost-stream side. This is because the projections 6 are particularly useful to move the coolant in the X-direction, this coolant having exchanged heat with the semiconductor element 21 on the upstream side and therefore has a temperature distribution in the X-direction, to thereby reduce this temperature distribution.

The projections 6 can be provided with ease, because they are formed in each of the shell plates 35. The projections 6 can be used as positioning means for positioning the straight fins 5 with respect to the shell plates 35 at the time assembling the cooling pipe 3. Other than the above, the third embodiment provides the same advantages as the first embodiment.

Fourth Embodiment

The fourth embodiment shown in FIGS. 11 to 15 is characterized in that the straight fins 5 are provided with the oblique ribs 53 projecting toward the divided coolant passages 323. As shown in FIG. 13, the oblique ribs 53 are inclined to the Y-direction and the cooling surface 33.

The oblique ribs 53 are press-formed in the side portions 52 of the straight fins 5.

In more detail, as shown in FIG. 12, each of the side portions 52 of the straight fins 5 is projectedly formed with the oblique ribs 53 at both surfaces thereof. Since the oblique ribs 53 on one of the surfaces of the side portion 52 and the oblique ribs 53 on the other surface cannot be formed so as to overlap each other, they are formed at positions shifted to each other as shown in FIG. 14 and FIG. 15. Since the oblique ribs 53 are press-formed, recess portions 531 are formed on the backside of the surface on whose front side the oblique ribs 53 are formed.

The inclination β of the oblique ribs 53 to the Y-direction may be 45 degrees. The projection height t2 of the oblique ribs 53 may be 1/10 of the fin gap t3 between two adjacent straight fins 5 (see FIG. 12). As shown in FIG. 11 and FIG. 13, the oblique ribs 53 are formed such that each two of them adjacent in the Y-direction have opposite inclinations. The others are the same as the first embodiment.

In this embodiment, because of the provision of the oblique ribs 53, there occurs pressure difference in the coolant in the X-direction, and therefore there occurs a flow with a velocity vector in the X-direction. This suppresses formation of a temperature distribution within the coolant passage 32.

In addition, since each two of the oblique ribs 53 adjacent in the Y-direction have opposite inclinations, the coolant in each of the divided coolant passages 323 flows in the Y-direction, while moving in the X-direction with being meandered by the oblique ribs 53. Hence, in this embodiment, the coolant can be moved smoothly in the X-direction. Other than the above, the fourth embodiment provides the same advantages as the first embodiment.

Fifth Embodiment

The fifth embodiment shown in FIG. 16, FIG. 17 and FIGS. 18A and 18B is characterized in that the straight fins 5 are provided with tapered ribs 54 projecting toward the divided coolant passage 323. The tapered rib 54 has such a tapered shape that the longitudinal direction thereof is along the X-direction as shown in FIG. 17, and the width thereof in the Z-direction gradually increases along the longitudinal direction thereof as shown in FIGS. 18A and 18B.

As shown in FIG. 16 and FIG. 17, each tapered rib 54 is provided at a position between each two of the semiconductor elements 21 adjacent in the Y-direction. Accordingly, in each of the divided coolant passages 323, each two of the tapered ribs 54 are disposed in series in the Y-direction on the upstream side of each of the semiconductor elements 21 except the one located on the uppermost-stream side. The two tapered ribs 54 disposed in series have different taper directions as shown in FIGS. 18A and 18B. Like the oblique ribs 53 in the fourth embodiment, the tapered ribs 54 in this embodiment can be formed by pressing the side portions 52 of the straight fins 5. The others are the same as the first embodiment.

In this embodiment, it is possible to vary the cross-sectional area of the divided coolant passage 323 along the X-direction at positions where the tapered ribs 54 are provided. This causes a flow of the coolant in the X-direction when the coolant passes the positions where the tapered ribs 54 are provided. Accordingly, according to this embodiment, it is possible to effectively suppress formation of a temperature distribution in the X direction. Other than the above, the fifth embodiment provides the same advantages as the first embodiment.

Sixth Embodiment

The sixth embodiment shown in FIG. 19 to FIG. 21 is characterized in that the cooling pipe 3 is provided with the middle plate 34 for dividing the coolant passage 32 in the X-direction to form the first passage 321 and the second passage 322, that these first and second passages are provided with the straight fins 5 formed so as to extend along the Y-direction to divide the coolant passage 32 in the Z-direction to thereby form a plurality of the divided coolant passages 323, and that the divided coolant passages 323 are provided with the projections 6 projecting toward the coolant passage 32.

As shown in FIG. 20, in this embodiment, the cooling pipe 3 includes the middle plate 34 dividing the coolant passage 32 in the X-direction to form the first passage 321 and the second passage 322 through each of which the coolant flows. Unlike the first embodiment, the middle plate 34 does not have the communicating portions 342 (see FIGS. 1 and 2), and accordingly the first passage 321 and the second passage 322 are not in communication with each other.

As shown in FIG. 20, the straight fins 5 are provided respectively in the first passage 321 and the second passage 322, such that they face each other across from the middle plate 34. The straight fins 5 are brazed to the shell plates 35 of the cooling pipe 3 at the top faces (crest portions and trough portions of the rectangular wave) 51 thereof. The straight fins 5 divide each of the first passage 321 and the second passage 322 in the Z-direction, to thereby form a plurality of the divided coolant passages 323.

As shown in FIG. 19, every other of the divided coolant passages 323 are formed with the projections 6. Each projecting positions 6 is provided at a position between each two of the semiconductor elements 21 adjacent in the Y direction. Accordingly, the projections 6 are located on the upstream sides of the semiconductor elements 21 except the one located on the uppermost-stream side.

As shown in FIG. 21, the projections 6 are formed by pressing the middle plate 4. The projections 6 are located at positions where the top faces 51 of the straight fins 5 do not abut on the middle plate 34. The projections 6 are formed projecting toward the first passage 321 and the second passage 322 alternately. The others are the same as the first embodiment.

In this embodiment, since the first and second passages 321 and 322 are provided with the projections 6, there occurs pressure difference in the coolant in the X direction, and therefore there occurs a flow with a velocity vector in the X direction. This suppresses formation of a temperature distribution in the coolant passage 32. In addition, since the projections 6 are located on the upstream sides of the semiconductor elements 21, the coolant moves short of each of the semiconductor elements 21 in the X-direction. Accordingly, since the low-temperature coolant approaches the semiconductor elements 21, they can be efficiently cooled.

The projections 6 can be provided with ease, because they are formed in the middle plate 34. The projections 6 can be used as positioning means for positioning the straight fins 5 with respect to the middle plate 34 at the time assembling the cooling pipe 3. Other than the above, the sixth embodiment provides the same advantages as the first embodiment.

The sixth embodiment described above may be modified as shown in FIG. 22 to FIG. 24. As shown in FIG. 23, in this modification, the straight fins 5 are provided in each of the first passage 321 and the second passage 322 such that they face the same direction with the middle plate 34 therebetween. As shown in FIG. 22, the projections 6 are provided in all the divided coolant passages 323. As shown in FIG. 24, the projections 6 have a rectangular wave shape similar to that of the straight fins 5, and formed to as to project toward the first passage 321 and the second passage 322 alternately. Other than the above, the sixth embodiment provides the same advantages as the first embodiment.

Seventh Embodiment

The seventh embodiment shown in FIGS. 25A and 25B is characterized in that the straight fins 5 are provided with the oblique ribs 53 formed projecting toward the divided coolant passages 323, the seventh embodiment having several variants with respect to locations and the number of the oblique ribs 53 provided. The basic structure of the seventh embodiment is the same as the fourth embodiment.

In the seventh embodiment shown in FIGS. 25A and 25B, the oblique ribs 53 are provided at six positions along the Y-direction. Each one of the oblique ribs 53 provided along the Y-direction belongs to any one of three oblique rib groups 53Y, each group including the oblique ribs 53 having the same oblique direction. The oblique directions of the oblique ribs 53 of two of the oblique rib groups 53Y adjacent in the Y-direction are opposite to each other.

In the variants of the seventh embodiment respectively shown in FIGS. 26A and 26B, and FIGS. 27A and 27B, the oblique ribs 53 are provided at eight position along the Y-direction, and at two or three positions along the X direction. Each two of the oblique ribs 53 adjacent in the Y-direction have opposite oblique directions. Each two of the oblique ribs 53 adjacent in the X-direction have opposite oblique directions.

In the variants of the seventh embodiment respectively shown in FIGS. 28A and 28B, and FIGS. 29A and 29B, the oblique ribs 53 are provided at eight positions along the Y direction, and at two or three positions along the X-direction. Each one of the oblique ribs 53 provided along the Y-direction belongs to any one of four oblique rib groups 53Y, each group including the oblique ribs 53 having the same oblique direction. The oblique directions of the oblique ribs 53 of two of the oblique rib groups 53Y adjacent in the Y-direction are opposite to each other. Each two of the oblique ribs 53 adjacent in the X-direction have opposite oblique directions.

In the variant shown in FIG. 30, the oblique ribs 53 are provided at eight positions along the Y-direction, and at four positions along the X-direction. Each one of the oblique ribs 53 provided along the X-direction belongs to either one of two oblique rib groups 53X, each group including the oblique ribs 53 having the same oblique direction. Each two of the oblique ribs 53 adjacent in the Y-direction have opposite oblique directions. The oblique directions of the oblique ribs 53 of two of the oblique rib groups 53X adjacent in the X-direction are opposite to each other.

In the variant shown in FIG. 31, the oblique ribs 53 are provided at eight positions along the Y-direction, and at four positions along the X-direction. Each one of the oblique ribs 53 provided along the Y-direction belongs to any one of four oblique rib groups 53Y, each group including the oblique ribs 53 having the same oblique direction. Each one of the oblique ribs 53 provided along the X-direction belongs to either one of two oblique rib groups 53X, each group including the oblique ribs 53 having the sane oblique direction. The oblique directions of the oblique ribs 53 of two of the oblique rib groups 53Y adjacent in the Y-direction are opposite to each other. The oblique directions of the oblique ribs 53 of two of the oblique rib groups 53X adjacent in the X-direction are opposite to each other.

In any one of the seventh embodiment and its variants, because of the provision of the oblique ribs 53, there occurs pressure difference in the coolant in the X-direction, and therefore there occurs a flow with a velocity vector in the X-direction. This suppresses formation of a temperature distribution in the coolant passage 32. The coolant in each at the divided coolant passages 323 flows in the Y-direction, while moving in the X-direction with being meandered by the oblique ribs 53.

Hence, in this embodiment, the coolant can be moved smoothly in the X-direction. Other than the above, the seventh embodiment provides the same advantages as the first embodiment.

Eighth Embodiment

The eighth embodiment shown in FIGS. 32A and 32B and its variant shown in FIGS. 33A and 33B are characterized in that the straight fins 5 are provided with the oblique ribs 53 and transverse ribs 55 projecting toward the divided coolant passages 323. The transverse ribs 55 are formed so as to be orthogonal to the Y-direction and the cooling surfaces 33. The basic structures of the seventh embodiment and its variant are the same as the fourth embodiment.

As shown in FIGS. 32A and 32B, in the eighth embodiment, the oblique ribs 53 are provided at four position along the Y-direction. Each two of the oblique ribs 53 adjacent in the Y-direction have opposite oblique directions. The transverse ribs 55 are provided at three positions so as to alternate with the oblique ribs 53 along the Y-direction.

In the variant shown in FIGS. 33A and 33B, the oblique ribs 53 are provided at four positions along the Y-direction, and at two positions along the X-direction. Each two of the oblique ribs 53 adjacent in the Y-direction have opposite oblique directions. Each two of the oblique ribs 53 adjacent in the X-direction have opposite oblique directions. The transverse ribs 55 are provided at five positions so as to alternate with the oblique ribs 53 along the Y-direction. The transverse ribs 55 are provided at two positions along the X-direction only at a middle one of the three positions along the Y-direction.

In the eighth embodiment and its variant, the coolant flowing through each of the divided coolant passages 323 moves in the X-direction because of the provision of the oblique ribs 53 and the transverse ribs 55. Accordingly, according to this embodiment and its variant, it is possible to effectively suppress formation of a temperature distribution in the X-direction. The coolant in each of the divided coolant passages 323 flows in the Y-direction, while moving in the X-direct ion with being meandered by the oblique ribs 53 and the transverse ribs 55. Hence, in this embodiment and its variant, the coolant can be moved smoothly in the X-direction. Other than the above, the eighth embodiment provides the same advantages as the first embodiment.

Ninth Embodiment

The ninth embodiment shown in FIG. 34 is characterized in that the straight fins 5 are provided only the transverse ribs 55 projecting toward the divided coolant passages 323. The transverse ribs 55 are formed so as to be orthogonal to the Y-direction and the cooling surfaces 33. Other than the above, the ninth embodiment provides the same advantages as the first embodiment. The basic structure of the seventh embodiment is the same as the fourth embodiment.

As shown in FIG. 34, in the ninth embodiment, the transverse ribs 55 are provided at eight positions along the Y-direction. The transverse ribs 55 formed in one of the shell plates 35 are located alternately with the transverse ribs 55 formed in the other shell plate 35.

In this embodiment, because of the provision of the transverse ribs 55, there occurs pressure difference in the coolant in the X-direction, and therefore there occurs a flow with a velocity vector in the X direction. Accordingly, according to this embodiment, it is possible to effectively suppress formation of a temperature distribution in the X-direction. The coolant in each of the divided coolant passages 323 flows in the Y-direction, while moving in the X-direction with being meandered by the transverse ribs 55. Hence, in this embodiment, the coolant can be moved smoothly in the X-direction.

Next, the advantageous effects of the projections, oblique ribs, and transverse ribs provided in the above described embodiments of the invention are explained in detail with reference to FIG. 35 and FIG. 36. As shown in FIG. 35, when the projections 6 are provided, there occur flows with velocity vectors indicated by W1, W2 and W3 in FIG. 35 in the direction perpendicular to the Y-direction (in the X-direction), because of pressure difference in the coolant W caused by the projections 6. This is because when the coolant W hits the projection 6, the coolant W flows along the projection 6 (W1), or circumvents the projection 6 to move to a low pressure side (W2). Even when the coolant W does not hit the projection 6, it moves to the low pressure side (W3).

As shown in FIG. 36, when the oblique ribs 53 are provided, there occur flows with velocity vectors indicated by W4, and W5 in FIG. 36 in the direction perpendicular to the Y-direction (in the X-direction), because of pressure difference in the coolant W caused by the oblique ribs 53. This is because when the coolant W does not climb over the oblique rib 53, it moves along the oblique rib 53 (W4), and when the coolant W climbs over the oblique rib 53, it moves to the low pressure side (W5). The transverse ribs 55 provide the same advantageous effect as the oblique ribs 53.

The above explained preferred embodiments are exemplary or the invention of the present application which is described solely by the claims appended below. It should be understood that modifications of the preferred embodiments may be made as would occur to one of skill in the art. 

1. A semiconductor cooling structure comprising: a semiconductor module including therein at least two semiconductor elements; a cooling pipe having a cooling surface in close contact with said semiconductor module, said cooling pipe including a coolant inlet hole, a coolant outlet hole, and a coolant passage through which coolant flows in a first direction from said coolant inlet hole to said coolant outlet hole; and a coolant moving structure disposed within said cooling pipe to move said coolant flowing through said coolant passage such that said coolant has a velocity vector in a second direction perpendicular to said cooling surface.
 2. The semiconductor cooling structure according to claim 1, wherein said coolant moving structure includes a middle plate disposed within said cooling pipe to divide said coolant passage in said second direction to thereby form a first passage and a second passage through each of which said coolant flows alternately.
 3. The semiconductor cooling structure according to claim 2, wherein said middle plate includes communicating portions for making a communication between said first and second passages at both end portions thereof in a third direction perpendicular to said first direction and parallel to said cooling surface, said coolant moving structure further including oblique fins provided in each of said first and second passages so as to extend obliquely to said first direction, an oblique direction of said oblique fins provided in said first passage being opposite to an oblique direction of said oblique fins provided in said second passage.
 4. The semiconductor cooling structure according to claim 1, wherein said coolant moving structure includes: straight fins disposed within said cooling pipe so as to extend in parallel with one another along said first direction to divide said coolant passage in a third direction perpendicular to said first direction and parallel to said cooling surface to thereby form a plurality of divided coolant passages; and projections located along said first direction in each of said divided coolant passages so as to project toward said coolant passage.
 5. The semiconductor cooling structure according to claim 4, wherein each of said projections is located on an upstream side of a corresponding one of said semiconductor elements.
 6. The semiconductor cooling structure according to claim 4, wherein said projections are formed in shell plates of said cooling pipe.
 7. The semiconductor cooling structure according to claim 1, wherein said coolant moving structure includes: a middle plate disposed within said cooling pipe to divide said coolant passage in said second direction to thereby form a first passage and a second passage through each of which said coolant flows separately; straight fins provided in each of said first and second passages so as to extend in parallel with one another along said first direction to divide said coolant passage in a third direction perpendicular to said first direction and parallel to said cooling surface to thereby form a plurality of divided coolant passages; and projections located along said first direction in each of said divided coolant passages, so as to project toward said coolant passage, said projections being formed in said middle plate.
 8. The semiconductor cooling structure according to claim 1, wherein said coolant moving structure includes: straight fins disposed within said cooling pipe so as to extend in parallel with one another along said first direction to divide said coolant passage in a third direction perpendicular to said first direction and parallel to said cooling surface to thereby form a plurality of divided passages; and oblique ribs provided in said straight fins so as to project toward said divided passages, said oblique ribs being inclined to said first direction and said cooling surface.
 9. The semiconductor cooling structure according to claim 8, wherein said oblique ribs are located at different positions along said first direction, each two of said oblique ribs adjacent in said first direction having opposite oblique directions.
 10. The semiconductor cooling structure according to claim 8, wherein said oblique ribs are located at different positions along said first direction, each one of said oblique ribs belonging to any one of oblique rib groups including a predetermined number of said oblique ribs having the same oblique direction, oblique directions of said oblique ribs of each two of said oblique rib groups adjacent in said first direction being opposite to each other.
 11. The semiconductor cooling structure according to claim 9, wherein said oblique ribs are further located at different positions along said second direction, each two of said oblique ribs adjacent in said second direction having opposite oblique directions.
 12. The semiconductor cooling structure according to claim 9, wherein said oblique ribs are further located at different positions along said second direction, each one of said oblique ribs belonging to any one of oblique rib groups including a predetermined number of said oblique ribs having the same oblique direction, oblique directions of said oblique ribs of each two of said oblique rib groups adjacent in said second direction being opposite to each other.
 13. The semiconductor cooling structure according to claim 8, wherein said coolant moving structure further includes transverse ribs provided in said straight fins so as to project toward said divided coolant passages, said transverse ribs being formed so as to extend in a direction perpendicular to said first direction and said cooling surface.
 14. The semiconductor cooling structure according to claim 1, wherein said coolant moving structure includes: straight fins disposed within said cooling pipe so as to extend in parallel with one another along said first direction to divide said coolant passage in a third direction perpendicular to said first direction and parallel to said cooling surface to thereby form a plurality of divided passages; and transverse ribs provided in said straight fins so as to project toward said divided passages, said transverse ribs being formed so as to extend in a direction perpendicular to said first direction and said cooling surface. 